U.S. patent application number 13/319376 was filed with the patent office on 2012-05-03 for method for producing a stable boric solution.
This patent application is currently assigned to TRIBOLATOR I NORDEN AKTIEBOLAG. Invention is credited to Tommy Lindblom, Magnus Unden.
Application Number | 20120108475 13/319376 |
Document ID | / |
Family ID | 43126377 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120108475 |
Kind Code |
A1 |
Lindblom; Tommy ; et
al. |
May 3, 2012 |
METHOD FOR PRODUCING A STABLE BORIC SOLUTION
Abstract
The invention relates to a method for producing a stable boron
solution with lubricating characteristics which is intended to be
used preferably as an addition in the form of a
concentrate/additive to a liquid, e.g. to a liquid fuel or a
lubricant. The invention is achieved by the method steps of using a
boron substance of pharmaceutical quality (1, 11), using a liquid
as solvent, applying a mixing ratio between the boron substance and
the solvent (3, 13) of preferably 1 g of boron per 15-25 litres of
liquid, agitating the mixture for an initial predetermined period
of time (4, 14), adding further liquid to dilute the solution (6,
15), the quantity of liquid being chosen such that a fmal user
mixture reaches a concentration of between 20 and 30 ppm of boron
(8), and further agitating the mixture (7, 16) for a second
predetermined period of time so that the boron substance is
completely dissolved in the boron solution, resulting in a boron
solution which is stable over time.
Inventors: |
Lindblom; Tommy; (Stockholm,
SE) ; Unden; Magnus; (Stockholm, SE) |
Assignee: |
TRIBOLATOR I NORDEN
AKTIEBOLAG
Stockholm
SE
|
Family ID: |
43126377 |
Appl. No.: |
13/319376 |
Filed: |
May 10, 2010 |
PCT Filed: |
May 10, 2010 |
PCT NO: |
PCT/SE2010/050510 |
371 Date: |
January 24, 2012 |
Current U.S.
Class: |
508/156 |
Current CPC
Class: |
C10M 125/26 20130101;
C10M 2201/087 20130101; C10L 10/08 20130101; C10N 2070/00 20130101;
C10L 1/1291 20130101; C10N 2030/02 20130101 |
Class at
Publication: |
508/156 |
International
Class: |
C10M 169/06 20060101
C10M169/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 8, 2009 |
SE |
0950323-6 |
Claims
1. A method for producing a stable boron solution with lubricating
characteristics which is intended to be used preferably as an
addition in the form of a concentrate/additive to a liquid, e.g. to
a liquid fuel or a lubricant, the method comprising the steps of
using a boron substance of pharmaceutical quality, using a liquid
as solvent, applying a mixing ratio between the boron substance and
the solvent of preferably 1 g of boron per 15-25 litres of liquid,
agitating the mixture for an initial predetermined period of time,
adding further liquid to dilute the solution, the quantity of
liquid being chosen such that a final user mixture reaches a
concentration of between 20 and 30 ppm of boron, and further
agitating the mixture for a second predetermined period of time so
that the boron substance is completely dissolved in the boron
solution, resulting in a boron solution which is stable over
time.
2. A method according to claim 1, comprising the further step of
agitating the solution so that its temperature rises but does not
reach the breakdown temperature of the liquid.
3. A method according to claim 1, comprising the further step of
using a solvent from among the category of organic liquids.
4. A method according to claim 1, comprising the further step of
using a solvent from among the category of inorganic liquids.
5. A method according to claim 1, comprising the further step of
using a boron substance in powder form.
6. A method according to claim 1, comprising the further step of
using a boron substance in the form of Borax H.sub.3BO.sub.3.
7. A method according to claim 1, comprising the further step of
using a boron substance in the form of boron oxide
B.sub.2O.sub.3.
8. A method according to claim 1, comprising the further step of
using a boron substance with a purity of at least 99%.
9. A method according to claim 1, comprising the further step of
using a solvent from among the category of kerosene, naphtha,
water, vegetable/synthetic/fossil oils, alcohol, methane,
hydrogen.
10. A method according to claim 1, comprising the further step of
the agitation being by means of a mechanical mixer.
11. A method according to claim 1, comprising the further step of
the agitation being by tumbling.
12. A boron solution with lubricating characteristics, primarily
intended as an addition in the form of a concentrate/additive to a
liquid, e.g. a liquid fuel or to a lubricant, made by a method
according to claim 1.
13. A concentrate/additive to a liquid, comprising a boron solution
with lubricating characteristics made by a method according to
claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing a
solution with lubricating characteristics. The invention relates
particularly to a method for producing a solution with lubricating
characteristics which contains boron and is preferably intended to
be used as an addition to a fuel or to a lubricant. The invention
relates more particularly to producing a stable concentrate of
dissolved boron which, when used in, for example, a machine or
engine, results in increased lubrication and reduced friction,
reduced risk of corrosion and reduced wear. The invention comprises
also the boron solution produced according to the method, and use
of such a boron solution.
TECHNICAL BACKGROUND
[0002] Various types of lubricant are used inter alia wherever
machine parts or engine parts are used. The better the lubricant
characteristics, the smaller the amount of energy consumed in
running the machines and the smaller the amount of wear on
constituent parts. It has for many years been known that the basic
substance boron has very good friction-reducing characteristics.
Empirical tests show that significant fuel savings can be made by
incorporating boron in lubricants and fuels, especially if the
particle sizes of the boron substance are within the range 0.5-100
nanometres. The advantageous lubricant effect is due to the ability
of boron to establish complex ligand bonds to metals, thereby
forming multi-dimensional plates between which the Van de Waals
forces are weak and which therefore easily slide relative to one
another. The boron substance forms a self-repairing system in that
new bonds to the metal continually replace worn-away material. In
addition, borate ions constitute, owing to their electronegativity,
an effective reducing agent which counteracts or prevents
corrosion.
[0003] Many attempts have been made to dissolve boron in various
liquids and lubricants. A problem has been to produce a water-based
boron solution in which the boron substance in desired particle
sizes and concentrations is completely dissolved in the liquid and
remains dissolved over time, such that the boron substance does not
precipitate and render the liquid turbid or settle out on the
bottom of the container in which the liquid/solution is placed.
[0004] Incorporating boron in a fuel or a lubricant by adding a
boron substance/compound is therefore prior art. Various methods
have also been patented.
[0005] U.S. Pat No. 6,368,369 (Advanced Lubrication Technology)
describes for example a method for mixing boric acid with, for
example, engine fuels to achieve friction-reducing characteristics.
This involves mixing the boric acid with a base oil and
endeavouring to ensure that the particle sizes of the boron are
between 0.5 and 20 micrometres, which is for example achieved by
so-called jet milling.
[0006] U.S. Pat. No. 6,783,561 (Foley & Lardner) refers inter
alia to a method whereby boron is added to and is in a "known way"
mixed with a fuel or a lubricant in a concentration of 30-3000 ppm.
There is no further indication as to how the actual mixing is
done.
[0007] SE524898 (Eagle Water Ltd) describes a procedure for
producing a boron solution in the form of a concentrate intended
for mixing with a liquid, e.g. a liquid fuel. The method amounts to
mixing a boron compound with a solvent and stirring and/or shaking
the resulting mixture, possibly by means of a mechanical
finely-dividing element and possibly at elevated temperature. The
boron content may be up to 250,000 ppm but is preferably within the
range 10-1000 ppm. The mixing method is not described in
detail.
[0008] Prior art thus indicates that boron is in a "known way"
mixed with a solvent, but does not indicate in more detail how to
achieve a solution with completely dissolved boron substance and in
which the boron substance remains completely dissolved, resulting
in a solution which is stable over time. There is for example no
indication of the initial boron substance or grade or how it is
treated/incorporated in order to be completely dissolved in the
liquid and remain stably dissolved over time. Further studies have
found that boron solutions produced by these known methods do not
remain stable over time, which is a significant and possibly
crucial problem with regard to being able to sell the solutions on
the market. It has thus been found that the boron particles in the
solutions do not become stably dissolved but readily aggregate and
over time gradually precipitate, resulting inter alia in the liquid
becoming turbid. The boron particles also settle out progressively
on the bottom of the container in which the solution is placed,
which may for example be the oil pan of a vehicle. The decreasing
boron content of the liquid greatly reduces the desired and
intended lubricating characteristics of the solution, and the
concentrated precipitation of boron may even cause damage to
engines and machines. For example, if precipitated boron in
concentrated form enters, for example, an engine, it will form
undesirable hard and harmful deposits throughout the engine, e.g.
on pistons, on exhaust valves, in pumps, in filters and on or in
other vital parts of the engine.
[0009] Prior art within this field thus does not indicate how to
solve the problem of achieving a boron solution which in desired
particle sizes and concentrations is non-turbid and stable over
time.
SUMMARY OF THE INVENTION
[0010] An object of the invention is to solve the above problem and
propose a method of the kind indicated in the introduction which
achieves a solution of boron in desired particle sizes and
concentrations, whereby the boron substance is completely dissolved
in the liquid and the resulting boron solution remains stable over
time and, when used for example in a machine or engine, results in
increased lubrication, reduced friction, reduced risk of corrosion
and reduced wear on constituent mechanical parts.
[0011] Another object of the invention is to propose a method which
is easy and inexpensive to make and hence to procure and use.
[0012] These and further objects and advantages are achieved
according to the invention with a method according to the features
indicated in the characterising part of claim 1.
[0013] The present invention thus relates to a method for producing
a boron solution with good lubricating characteristics which is
intended primarily to be used as an addition to a fuel or a
lubricant. The method involves boron powder of a specific grade
being mixed with a solvent in a number of steps and in a certain
mix ratio. The mixture undergoes mechanical agitation in at least
two steps between which further liquid, solvent, is added, during
which agitation the temperature of the mixture may be allowed to
rise.
[0014] Further features and advantages, of the invention are
indicated by the more detailed description of the invention set out
below and the accompanying drawings and other claims.
BRIEF LIST OF DRAWINGS
[0015] The invention is described in more detail below in various
preferred embodiments with reference to the attached drawings.
[0016] FIG. 1 is a flowchart illustrating the method steps
according to the invention which lead to a boron solution which is
non-turbid and stable.
[0017] FIG. 2 is a further flowchart illustrating an alternative
method for achieving a stable boron solution.
[0018] FIG. 3 depicts from above a device for treating any desired
liquid with a boron substance.
[0019] FIG. 4 depicts the device in FIG. 3 but as seen from the
side.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0020] The present invention thus relates to a method whereby
boron, e.g. in the form of a boron compound, is added to and finely
divided/dissolved in a liquid in such a way as to cause the boron
substance to remain stably dissolved in the liquid over time.
[0021] It is for example possible to use a boron compound such as a
crystalline boric acid, boron oxide, boron trioxide etc. It is
preferable to use an oxygen-bearing boron compound H.sub.3BO.sub.3
in the form of a powder, which is therefore a white crystalline
boric acid of pharmaceutical quality, i.e. with a purity of
preferably at least 99% and a molecular weight of 61.8 g/mol. An
alternative is to use boron oxide B.sub.2O.sub.3, with a molecular
weight of 69:6 g/mol, also known as anhydrous boric acid, which
does not contain water. Boron oxide is therefore boric acid without
water content and is usable in the same way as boric acid. Boron
oxide is converted spontaneously to boric acid by water, e.g. by
condensate.
[0022] The liquid with which the boron substance or the boron
powder is to be mixed is preferably an organic and/or inorganic
liquid or a gas. Examples of such liquids are kerosene, naphtha,
water, vegetable/synthetic/fossil oils, alcohol. Examples of
suitable gases are methane, hydrogen etc. The amount of liquid may
be in small batches, e.g. of about 3 litres, but may also be, for
example, about 1000 litres per batch.
[0023] It is important to use/achieve boron particles which are of
small particle size. The boron particles used as initial material
from the outset range from 1 millimetre to 10 micrometres in
size.
[0024] It is also advantageous that negative electrostatic charging
of the boron particles be achieved during the mixing. If an alcohol
is chosen as solvent, its hydrogen bonds will counteract the
electronegativity of the boron compound and hence the latter's
inherent tendency to covalent bonding. The boron particles may be
given a negative electrostatic charge by vigorous stirring, e.g. by
means of mixer blades or the like, in which case the blades may
preferably have a wing profile and be twisted and provided with
winglets.
[0025] The Mixer Method
[0026] In this method, the mixing of the boron substance and the
liquid comprises two main steps, in at least one of which a mixer
is used. The configuration of the mixer blades needs to be such
that there are major pressure differences between their upper and
lower sides. Their profile needs a blunt forward edge and a sharper
rear edge and the blade setting needs to be between 0.5 and about 3
degrees, preferably about 2 degrees. The setting is adapted to
achieving a more uniform angle of incidence across the surface,
since the blade profile moves at different velocities through the
liquid, depending on how far away from the centreline the blade
meets the liquid and the particles mixed with it. The most suitable
blades have a profile which allows laminar flow across and past the
thickest part of the profile chord, i:e. where the profile is more
than 20% of the chord, as measured from the forward edge of the
profile. The sharper termination of the profile causes the liquid
and its particles to be brought together/mixed at different
velocities. Suitable blade profiles available on the market may be
Clark Y.TM., NACA-6.TM. series or SG6042.TM.. It is important that
the profile has a low Reynolds number and that the thickness is
about 12% of the chord. The nature of the flow is of course
affected by the viscosity of the liquid. The time taken to achieve
the desired final result will depend on the blade configuration.
The very finest boron particles are obtained by mutual abrasion and
collision with other boron particles in the liquid. Such collisions
take place largely at the rear edge of the blade where the
liquid/the particles meet at high velocities.
[0027] A step for achieving a stable boron solution is to use a
boron substance with certain specific characteristics, method step
1. The choice of the boron substance greatly affects the final
result. The boron substance which meets the requirements of this
method is Borax H.sub.3BO.sub.3 in powder form and of
pharmaceutical quality, i.e. a boron substance with a purity of
preferably at least 99% and a molecular weight of 69.6. Boron oxide
B.sub.2O.sub.3, also known as anhydrous boric acid, which is a
water-free boric acid, is also usable.
[0028] A further step is to choose a liquid or solvent in which the
boron substance or the boron powder is to be incorporated, method
step 2. This liquid is preferably an organic and/or inorganic
liquid or a gas. Examples of conceivable liquids are kerosene,
naphtha, water, vegetable/synthetic/fossil oils, alcohols, and
examples of conceivable gases are methane, hydrogen etc.
[0029] A further step is to use a predetermined mix ratio between
the boron powder and the liquid, method step 3. This is a crucial
factor for achieving the product according to the invention. The
mix ratio needs to be about 1 to 25 by weight, i.e. mixing about 4
parts of boron with 100 parts of liquid/solvent. The ratio may of
course vary somewhat, e.g. depending on the temperature of the
solution at the time of mixing, but also on what the solution is
ultimately intended for. If the solution is intended for
application in diesel fuel, a mix ratio of about 1/1000 is
employed.
[0030] The next step is to mix the components, method step 4, with
one another and treat the mixture/solution mechanically, e.g. in a
mixer provided with blades. The mixer agitates the mixture at high
speed, i.e. about 15,000 rpm, for an initial predetermined period
of 15-20 minutes, resulting in an initial solution, method step 5.
The temperature of the solution may rise at this stage but must
never exceed the breakdown point of the solvent, e.g. oil. The
initial mixing thus takes place in liquid of low viscosity mainly
involving uncharged particles and resulting in boron particles in
micrometre sizes. The mixing takes place at a blade periphery
velocity of about 800 km/h for 15-20 minutes and generates a
temperature rise from normal room temperature of 20 degrees to
about 50-60.degree. C. The mixing takes place with advantage at
atmospheric pressure. Thereafter, further liquid, e.g. an oil, is
added, method step 6.
[0031] The next step is to run the mixer for a second predetermined
period of about a further 15 minutes, method step 7. The
temperature of the solution is allowed to rise but not to reach the
breakdown temperature of the liquid. If oil is used, the
temperature should not exceed 80.degree. C. This second mixing,
which leads to the final product, thus takes place in liquid of
higher viscosity and generates particles of nano size and also
charges the particles electrically. The mixing takes place at a
periphery velocity of about 800 km/h and proceeds for 30-40
minutes, generating during that time a temperature rise to about
70-80.degree. C. The mixing takes place at atmospheric pressure.
The periphery velocity of the blades should be between 500 and 800
km/h. Lower velocities result in longer mixing times and greater
attraction forces between particles, with consequently more
settling out and clustering of the final product.
[0032] The temperature of the liquid at the commencement of mixing
may be between -25.degree. C. and +75.degree.. The initial
temperature has little effect on the final result and/or on the
mixing time.
[0033] The temperature rises during the mixing because of the
kinetic energy developed. At 170.degree. C. boric acid begins to
form crystals, thereby disrupting the solution. As previously
mentioned, the temperature reached on completion of mixing should
not exceed 80.degree. C.
[0034] Thereafter, further liquid is added, method step 8, and the
solution is further mixed for, say, 10-15 minutes. The amount of
liquid incorporated in the solution is such that a final user
mixture, i.e. that resulting from the final customer incorporating
the additive in a desired engine fuel, exhibits a concentration of
about 20-30 ppm in the user mixture (e.g. the engine fuel).
[0035] After particles larger than 100 nanometres have had the
opportunity to settle out, method step 9, the final product is
drawn off into a suitable container, method step 10.
[0036] The Tumbling Method
[0037] A first step for achieving a stable boron solution with this
method is to use a boron substance with specific characteristics,
method step 11. The choice of the boron substance greatly affects
the final result. The boron compound may for example consist of
crystalline boric acid, boron oxide, boron trioxide etc. It is
preferable to use an oxygen-bearing boron compound H.sub.3BO.sub.3
in the form of a powder, which is therefore a white crystalline
boric acid of pharmaceutical quality, i.e. with a purity of
preferably at least 99% and a molecular weight of 61.8 g/mol. An
alternative is to use boron oxide B.sub.2O.sub.3, with a molecular
weight of 69.6 g/mol, also known as anhydrous boric acid, which
does not contain water. Boron oxide is boric acid without water
content and is usable in the same way as boric acid. Boron oxide is
converted spontaneously to boric acid by water, e.g. by
condensate.
[0038] The next step is to choose and use liquid/solvent in which
the boron substance or the boron powder is to be incorporated,
method step 12. In this case, alcohol with a percentage by volume
of at least 95%, preferably 99.5% or higher, is chosen. The liquid
may also be an organic and/or inorganic liquid or gas. Examples of
conceivable liquids are kerosene, naphtha, water,
vegetable/synthetic/fossil oils. Examples of conceivable gases are
methane, hydrogen etc.
[0039] The next step is to apply a certain mix ratio which in this
method is chosen such that between 0 and 300 g of boron substance,
preferably about 20-30 g, is used per litre of liquid, method step
13. The mix ratio depends on the final purpose for which the
mixture is to be used. The higher concentration is intended for
additives for oils which are not consumed in, for example, an
engine or for chains etc., whereas the lower mix ratio is employed
for oils/fuels which are consumed, e.g. two-stroke oil/fuel.
[0040] The next step is to tumble the mixture, i.e. placing it in a
rotating drum which is provided with internal paddles or contains
steel balls or similar mixing means and is rotated at a speed
appropriate to the purpose, e.g. 2-10 rpm, for an initial
predetermined period of preferably 8-10 hours, method step 14. The
tumbling procedure is preferably conducted at room temperature but
may of course also be conducted at other temperatures, e.g. at
elevated temperature.
[0041] Thereafter, further liquid, diluent, is added, method step
15, in such quantity that a final user mixture arrived at by the
final customer incorporating the additive according to mixing
instructions in the respective engine fuel exhibits a concentration
of about 20-30 ppm. This step is followed by further mixing for a
second predetermined period, method step 16.
[0042] Boron particles which are of too large a particle size, i.e.
those larger than 100 nm, are thereafter separated, e.g. by
settling out, method step 17.
[0043] Thereafter the solution, the final product/the additive, is
drawn off into suitable containers, e.g: plastic bottles, method
step 18. The final customer will subsequently add the additive to
the respective engine fuel, according to mixing instructions,
preferably in a proportion of 1 to 1000, resulting in a final boron
concentration in the engine fuel of preferably about 20-30 ppm.
[0044] The boron substance is thus incorporated in, for example, a
base liquid, thereby creating a concentrate or additive which, for
the purposes of use, is diluted in a further liquid, preferably in
a propellant such as petrol in various forms, e.g. alkylate, avgas
100LL, avgas 91/96, possibly with incorporation of various
alcohols, methanes etc. The propellant may also be diesel fuel in
various forms, e.g. diesel oil, synthetic diesel fuel, RME, REE, FT
diesel fuel, kerosenes, naphthas, etc. The further liquid may also
be water in various forms, e.g. vapour, or
vegetable/synthetic/fossil oils. Various gases are also
conceivable, e.g. hydrogen gas, liquid hydrogen etc.
[0045] The boron content of the concentrate/the additive may for
example be up to 250,000 ppm or more. The finished fuel mixture,
after adding the additive, should reach a boron content within the
range 10-10,000 ppm, preferably within the range 20-30 ppm. The
higher concentration, up to 10,000 ppm, pertains primarily to use
in pure lubricants.
[0046] The boron solution according to the invention may with
advantage also be used in, for example, rust-protecting/lubricating
sprays or food industry applications and need not be
protection-classified. The boron solution is also usable as mould
oil, e.g. in concreting with sliding formwork, or as cutting fluid,
in which the boron compound will also have an antibacterial effect.
The solution may also serve as an oil-free lubricant for the metal
pressing industry, making it possible to eliminate oil recovery
after the pressing process.
[0047] The solution/the additive may of course also be used
directly or indirectly as a lubricating agent in organic and/or
inorganic liquids and gases, it may also reduce the amount of
expensive and environmentally more pollutant products.
[0048] Use in vehicle fuels achieves further advantages in that
pumps, injection nozzles, etc. are more effectively lubricated.
[0049] FIG. 3 depicts from above a device 19 for treatment of a
liquid with a boron substance. A plurality of spray nozzles 21a-c,
a metal plate 22, a supply pipe 23 and a gathering channel 24 are
disposed in a substantially closed treatment chamber 20. A boron
solution under pressure is supplied to the treatment chamber 20 via
thespray nozzles 21a-c in such a way that the boron solution is
sprayed at the liquid. The spray nozzles 21a-c are therefore
directed towards the metal plate 22. Untreated liquid, e.g. oil, is
supplied to the treatment chamber 20 and the metal plate 22 via the
supply pipe 23 and is distributed via holes 25 in the supply pipe
23. The oil or liquid is distributed evenly across and runs down
the sloping metal plate 22 towards the gathering channel 24. The
pressure of the incoming oil or liquid and the angle ofthe sloping
metal plate 22 affect the flow velocity and therefore the time of
exposure to spray from the spray nozzles 21a-c. The device may be
used for various different types of liquids.
[0050] The metal plate 22 is connected by an electrical conductor
to a voltage source and is preferably supplied with a positive
voltage potential, whereas the spray nozzles 21a-c are connected to
the negative potential of the voltage source. The voltage level may
be adjusted to a voltage appropriate to the purpose. This
electrostatic method and spray device make it possible to achieve
more effective incorporation of the boron substance in the
liquid.
[0051] The voltage potential may also be reversed, in which case
the metal plate 22 becomes negative and the spray nozzles 21a-c
positive.
[0052] The pressure of the boron solution supplied to the spray
nozzles 21a-c is adjustable, as also the amount of boron dissolved
in the solvent. The gathering channel 24 evacuates treated liquid,
e.g. oil, to an external gathering vessel (not depicted). The
treatment chamber 20 is with advantage subjected to positive
pressure which is adjusted by means of a valve (not depicted) so
that the finished oil mixture exhibits a correct flow velocity. The
metal plate 22 is insulated from the treatment chamber 20 by
insulators 26. The spray nozzles 21a-c are connected by hoses or
pipes 27 to an external pressurised container (not depicted) which
contains the solvent, the boric acid.
[0053] FIG. 4 depicts the device in FIG. 3, but as seen from the
side. It shows clearly how the metal plate 22 slopes relative to
the mixing chamber 20. An evacuation pipe 28 is provided to
intercept and recover surplus boron mixture.
[0054] The above description is primarily intended to facilitate
comprehension of the invention. The invention is of course not
limited to the embodiments indicated, since other variants of it
are also possible and conceivable within the scope of the concept
of the invention and within the scope of protection of the claims
set out below. Thus the boron solution/the additive may also be
suitably applied directly to whatever is to be lubricated, without
being first mixed with some other liquid such as a propellant or
lubricant.
* * * * *